Welcome to Boston, where the "broker fee" is a time-honored tradition. Waaay back in 2001, a friend of mine was moving out of her apartment at the same time I was looking for one. I ended up paying one months' "broker fee" and all the broker did is literally hand me the key.

When my lease was up, my landlord (I think he owned a bunch of apartments) tried to sue me for not returning the keys to the broker.

You didn't get scammed any more than anyone else who rents in the city. If anything you should look at all paperwork and check to see if the "written notice" was there in 5-point text.